Guest-Binding-Induced Interhetero Hosts Charge Transfer Crystallization: Selective Coloration of Commonly Used Organic Solvents

Unprecedented interheteromacrocyclic hosts charge transfer (CT) crystals were generated by cooling organic solutions containing p-dimethoxybenzene-constituted pillar[5]arene (P5A) and p-benzoquinone-constituted pillar[5]quinone (P5Q). Despite the weak CT interaction known between p-dimethoxybenzene and p-benzoquinone and the lack of formation of CT complexes between P5A and P5Q in the solution phase, CT cocrystals between PSA and P5Q were formed with solvent molecules included into the hosts' cavities. Such a cocrystallization arises from an elegant synergy between the CT interaction and solvent-binding-promoted crystallization. The interhetero hosts CT crystals were studied by optical and electron microscopic techniques, X-ray powder diffraction, solid-state NMR, UV-vis, IR spectroscopic studies, and X-ray single-crystal studies. The solvent complexation was critical for formation of the supramolecular CT microcrystals. The CT absorption bands faded upon removing the solvent molecules under vacuum, but they could be recovered by reuptake of the solvent molecules. Intriguingly, the CT absorption bands and uptake kinetics are distinguishably different for various organic solvents, thus providing a unique way to distinguish between different commonly used chemicals.

通过冷却含有对二甲氧基苯构成的柱[5]芳烃（P5A）和对苯醌构成的柱[5]醌（P5Q）的有机溶液，生成了前所未有的异质大环主体电荷转移（CT）晶体。尽管已知对二甲氧基苯和对苯醌之间的电荷转移相互作用较弱，且在溶液相中P5A和P5Q之间未形成电荷转移复合物，但P5A和P5Q之间形成了包含溶剂分子于主体空腔内的电荷转移共晶体。这种共结晶源于电荷转移相互作用和溶剂结合促进结晶之间的巧妙协同作用。通过光学和电子显微镜技术、X射线粉末衍射、固态核磁共振、紫外 - 可见光谱、红外光谱研究以及X射线单晶研究对异质主体间的电荷转移晶体进行了研究。溶剂络合对于超分子电荷转移微晶的形成至关重要。在真空下除去溶剂分子时，电荷转移吸收带减弱，但通过重新吸收溶剂分子可使其恢复。有趣的是，对于不同的有机溶剂，电荷转移吸收带和吸收动力学明显不同，从而为区分不同的常用化学品提供了一种独特的方法。